1. Field of the Invention
The present invention relates to an electrolytic cell, particularly for parting gold and silver from a material containing these noble metals. This cell is such as to remove gold and silver separated from each other without stopping the treatment. However, the cell of the invention can be used for other similar applications.
2. Description of the Prior Art
It is well known that in the plants for gold and silver working it is very important to recover of the precious metals that are in the form of working shavings or dust which can fall either on the ground or on the workmen's overalls whereby it is necessary to carry out a recovery operation by treating the washing waters of the garments as well as the waste or the like.
Normally, such wastes are treated so as to extract all the metallic materials contained therein, which besides the above mentioned precious metals, may sometimes include also other metals, in particular copper. Therefore, the wastes are subjected to several treatments among which is a thermal one, in order to eliminate the remainder of not metallic materials so as to obtain, by way of casting, the plates containing Cu, Ag and Au. From these plates the gold and the silver is extracted by means of an electrolytic process carried out in a plant in which a plurality of anodes and cathodes contained within at least one vessel are operated in a cascade connection and wherein filtering bag frames of porous tissue containing an anode plate consisting of the material to be treated, which includes Au and Ag, are removable suspended. Outside thereof, a bath proof cathode plate, consisting particularly of stainless steel, is also suspended.
These electrodes are respectively connected in parallel in a network supplied by a d.c. source. The bath consists of a solution of nitric acid and silver nitrate.
Plants are well known wherein silver particles are formed on the cathode and are collected on the vessel bottom, while the gold particles are formed on the anode and collected on the bottom of the filtering bags.
Therefore, after the plant is operated for a predetermined time the working is stopped in order to draw the gold by extracting the filtering bags and to take up the silver from the vessel bottom where the silver crystals are deposited. This stoppage involves a long and labourious operation that lowers the plant efficiency.